Molecularly imprinted polymer for selective determination of Δ9-tetrahydrocannabinol and 11-nor-Δ9- tetrahydrocannabinol carboxylic acid using LC-MS/MS in urine and oral fluid

Abstract

The use of molecularly imprinted polymers (MIPs) for solid phase extraction (MISPE) allows a rapid and selective extraction compared with traditional methods. Determination of Δ(9)-tetrahydrocannabinol (THC) and 11-nor-Δ(9)-tetrahydrocannabinol carboxylic acid (THC-COOH) in oral fluid (OF) and urine was performed using homemade MISPEs for sample clean-up and liquid chromatography tandem mass spectrometry (LC-MS/MS). Cylindrical MISPE shaped pills were synthesized using catechin as a mimic template. MISPEs were added to 0.5 mL OF or urine sample and sonicated 30 min for adsorption of analytes. For desorption, the MISPE was transfered to a clean tube, and sonicated for 15 min with 2 mL acetone:acetonitrile (3:1, v/v). The elution solvent was evaporated and reconstituted in mobile phase. Chromatographic separation was performed using a SunFire C18 (2.5 μm; 2.1 × 20 mm) column, and formic acid 0.1% and acetonitrile as mobile phase, with a total run time of 5 min. The method was fully validated including selectivity (no endogenous or exogenous interferences), linearity (1-500 ng/mL in OF, and 2.5-500 ng/mL in urine), limit of detection (0.75 and 1 ng/mL in OF and urine, respectively), imprecision (%CV <12.3%), accuracy (98.2-107.0% of target), extraction recovery (15.9-53.5%), process efficiency (10.1-46.2%), and matrix effect (<-55%). Analytes were stable for 72 h in the autosampler. Dilution 1:10 was assured in OF, and Quantisal™ matrix effect showed ion suppression (<-80.4%). The method was applied to the analysis of 20 OF and 11 urine specimens. This is the first method for determination of THC and THC-COOH in OF using MISPE technology.